[smoothdeveloper]

Never under-estimates wrong defaults in a language, for example:

C++, const modifier, verbose for more correct code (less mutable state, etc.) Rust, mut modifier, verbose for less correct code

C/C++, bothersome to have tight scopped values, due to split of expression & statement ML languages, nesting of let bound values, everything is tight scoped, even recycling local names non destructively via shadowing.

C#: mostly, all flaws of C/C++/Java F#: mostly all right things of ML, OCaml, Rust

F#: Structural comparison of ML types from day 1 C#: just adding records recently; most of libraries, idioms, and semantics geared towards reference comparison

idioms

C#: mainly OO, noisy syntax, low expressivity (constructing immutable values out of generators or expressions), lots of navigation due to adhoc things needed to be named, poor type inference F#: data & functions, concise end non noisy syntax, high expressivity (list expressions, computation expression values), less scrolling & navigation, object expression rather than defining type used once, great type inference (less noisy diff on refactorings)

etc.

So average F# codebase is by construct, more sound, than average C# codebase, however F# code quality may be poor, and C# great, still, more soundness in F#, IMHO.